About the town » Plum, Allegheny County, Pennsylvania, United States

For the township in Venango County, see Plum Township, Pennsylvania.Plum is a borough in Allegheny County in the U.S. state of Pennsylvania. The population was 27,126 at the 2010 census.Plum is often referred to as "Plum Boro" or more correctly "Plum Borough" by locals to distinguish it from its previous status as a township. It was founded as Plum Township in 1788 and was reorganized as a borough in 1956.